Mac Pro - Memory Question

Discussion in 'MacBook Pro' started by ikarus79m, Sep 30, 2006.

  1. ikarus79m macrumors member

    Sep 30, 2006
    Hey guys,

    I just ordered a mac pro with 4x512 MB (2gig) from apple and would like to upgrade 1-2 more Gigabites over the next few weeks. I am wondering if I have to continue to buy 512MB modules, or if I can mix my existing 512MB modules with 1gig or even a single 2gig module. Does this work? Does it affect performance?

    I am also looking at third party ram, in particular from DealRam.

    It says that it is Mac Pro certified and is pretty cheap. Any comments?
  2. Sun Baked macrumors G5

    Sun Baked

    May 19, 2002
    Must be added in pairs ...

    Mac Pro Memory (FB-DIMM) DIY Replacement Instructions (pdf)

    An yes, anything other 4x??GB/MB arrangement will affect performace, since the machine is capable of quad channel operation using 4 matched DIMMs split between Riser A & B.

    But more memory will trump the loss of perfomace caused by falling back to dual channel operation.
  3. ikarus79m thread starter macrumors member

    Sep 30, 2006
    So if I understand that document correctly, that means that in addition to the 2 pairs of 512MB in my 2GB configuration, I could add an aditional pair of 1GB modules to bring up my total to 4GB correct?

    As long as I always install in pairs the same size and manufacturer I am fine correct? (Meaning I don't have to install only 512MB modules just because my first two pairs are 512 modules.)
  4. robbieduncan Moderator emeritus


    Jul 24, 2002
    You can install 2x1Gb (or even 2x2Gb) modules into the spare slots it you want. It's (marginally) faster to access the first pair of slots on each riser than the second pair so if you are doing this put the larger modules in the first slots as they will probably be accessed more (as they will be at the bottom of the memory space). This will minimise the amount of slower RAM.
  5. ikarus79m thread starter macrumors member

    Sep 30, 2006

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